This invention relates to termite detectors, concentrators and feeders. It also relates to a method of deploying such devices in concert as a means of detecting, concentrating and suppressing existing termite colonies and protecting a monitored area from future attacks by subterranean termites.
The cyclodienes chlordane, first introduced in 1945, and heptachlor were generally regarded as the most effective termiticides in history. They provided 100% control of subterranean termites for 20-30 years or more.
Although chlorinated hydrocarbons had been described since 1873, their insecticidal properties were not discovered until 1939 when Paul Muller, who later received a Nobel prize for doing so, demonstrated the efficacy of DDT. During World War II DDT was credited with saving literally thousands of lives. Later its effectiveness in the field of disease vector control led many to mistakenly believe that it might end the scourge of malaria forever. Not surprisingly, DDT and the related chlorinated hydrocarbons dieldrin, aldrin, chlordane and heptachlor were tested and used extensively as termiticides. For their part, chlordane and heptachlor proved extremely effective against subterranean termites, particularly because, even at low rates of application they remained effective in the soil long after the soil was treated.
The extraordinary persistence of the cyclodienes, which helped make them famous as termiticides and as agricultural pesticides, also led to their downfall. It was shown that they accumulated in the food chain, where processes such as biomagnification increased the risk of injury to non-target organisms, including humans.
After the EPA was established in 1970 data began to surface showing noticeable residues of oxychlordane in human fat tissue. Because of these concerns the use of cyclodienes on food crops in the U.S. was banned. Later, despite intense lobbying by the pest control industry, they were further banned from the field of termite control, effective in the month of April, 1987. Other countries followed suit until, today, neither chlordane nor heptachlor may be legally applied anywhere in the world.
This action, while warranted, left a significant void. No equivalent soil drench termiticides have since been discovered to replace the cyclodienes.
In the early 1980""s, as it appeared that the days of the cyclodienes as termiticides were numbered, several alternative chemicals were registered with the EPA. Since that time, the number of such alternative products has risen sharply. Reports surfacing not long after the 1987 ban indicated that many of these not only worked as well, but were even more effective than the cyclodienes. However, the new products only lasted in the soil for a few years. Furthermore, their longevity was affected by type, pH, and organic content of the soil. Even under favorable conditions, a significant depletion of termiticide occurred by the end of the fifth year following application.
Homeowners and businesses in the United States of America annually spend in excess of $1.7 billion to combat termite infestations. Therefore a sizeable market for effective termite extermination products and methods exists in this country. Significant expenditures also occur on the European continent, in Asia, and in Australia. Termite damage to wooden structures is a phenomenon that spans the globe. The need for effective termite control exists throughout much of the populated world.
Recent Termite Control Developments
Approximately 160 patents relating to termite control were issued by the U.S. Patent Office between 1971 and the end of 1998. Some 108 of these, representing 68% of the total, were filed after the cyclodienes were banned in 1987.
Almost 39% of the termite-related patents issued over the past 26 years involved new termite toxicants. Many of these are used in the same manner as the cyclodienes, i.e., as soil drenches, serving as repellents and barriers against termite infestation. Others are intended to suppress a termite colony""s population by poisoning or otherwise rendering ineffective a large number of its members. In this latter group are found contact poisons, biological agents, e.g. Metarrhizium anisopliae, gastrointestinal poisons, e.g., Sulfluramid, and insect growth regulators and chitin synthesis inhibitors, e.g., Hexaflumuron.
A number of physical barriers have also been invented during this period. For example, U.S. Pat. No. 5,417,017 discloses a stainless steel mesh that is woven so tightly that termites are unable to pass through it.
Besides new toxicants and physical barriers, new methodologies for creating safer, more effective methods of applying chemically based termite barriers have been invented as well. Some of these seek to reduce the risk of human exposure to chemicals:
U.S. Pat. No. 5,465,525 issued Nov. 14, 1995 teaches utilizing a computer-controlled robot having an array of sensors, video linkages and pesticide dispensers. Human operators are located remotely where, safe from chemical exposure, they are able to identify where and how extensively termiticides should be dispensed by the robot beneath architectural structures.
U.S. Pat. No. 5,346,699 issued Sep. 13, 1994 teaches using a wet foaming agent to allow a relatively small amount of termite toxicant to create a termite barrier in a void. The foam is used to fill voids in walls and under concrete foundations and walkways, wetting all surfaces of the void before collapsing. Consequently, termites passing over any surface of the void will receive a dose of the toxicant.
U.S. Pat. No. 5,317,831 issued Jun. 7, 1994 teaches using a permanently installed system of tubes and nozzles to periodically deliver measured amounts of liquid termite control fluids throughout the hard-to-reach sub-floor region of structures with pier and beam foundations. Similarly, U.S. Pat. No. 5,819,466 issued Oct. 13, 1998 describes a system that performs an analogous service around the perimeters of homes with monolithic concrete foundations.
New approaches have also been developed in the fields of termite detection, monitoring and baiting. When termite colonies are detected early in their development the door is open to suppress them before they can cause any significant damage.
Detection, monitoring and baiting methods focus on pinpointing active termites and feeding them small, measured amounts of termite-specific toxicants. These are contained in tamper resistant bait servers, and act to reduce the population of the termite colony to the point where it cannot infest entities of economic value.
The process of reducing the population of the termite colony to the point where it cannot infest entities of economic value is referred to in the scientific literature as xe2x80x9csuppression and/or eliminationxe2x80x9d. However, the cryptic nature of subterranean termites makes it difficult or impossible to be certain that colony elimination has taken place. For this reason this process will be referred to in this document as xe2x80x9csuppressionxe2x80x9d.
Once the termites in a specified area have been successfully suppressed, the area is monitored indefinitely for new signs of active termites. If new signs of active termites are found, a new round of toxicant baiting is initiated.
Termite detection and baiting has been investigated and tested to some degree since before the turn of the century. Scientific interest in this method began to increase in the late 1960""s, and continued at a low level in the 1970""s and early 1980""s. However, the skill and experience required to properly implement detection and baiting methodologies discouraged widespread exploration for technically or economically feasible approaches as long as the highly successful and inexpensive cyclodienes could be used. Following the 1987 ban a number of important advances in each of these fields has occurred in quick succession:
An acoustic emission detector, capable of sensing the vibrations produced by termites when they break the cellulose and lignin fibers of the wood they are consuming, is described in U.S. Pat. No. 4,895,025 issued Jun. 26, 1990. Since that date at least five other acoustic or vibration sensing devices have also been patented.
A system for detecting, monitoring and baiting termites is described in U.S. Pat. No. 5,676,960 issued Oct. 14, 1997 and U.S. Pat. No. 5,509,879 issued Mar. 11, 1997. These systems use a comprehensive termite detection, trapping, separation and treatment methodology to aggregate large numbers of the members of a termite colony. The termites are then manually coated with a termite toxicant mixed with an adhesive resin and released. Once the coated termites return to the colony the untreated workers instinctively groom them to remove the toxicant coating. In the process, the previously untreated workers contaminate themselves and their nest mates with lethal doses of the toxicant material.
Another termite detection, monitoring and baiting system is described in U.S. Pat. No. 5,329,726 issued Sep. 8, 1992. The apparatus described in this patent involves an in-ground termite detector/server combination containing a detector cartridge that is initially non-toxic. When termites begin feeding on the contents of this cartridge they and the physical damage they cause are noticeable to an inspector, but only after the cartridge has been physically withdrawn from the detector/server housing. Once termites are detected, the detector is converted to a pesticide-containing bait server by discarding the non-toxic feeder cartridge and replacing it with one containing a pesticide. Modifications to the in-ground apparatus that provide for aboveground termite detection and control are also described.
A later patent granted to the same inventors, U.S. Pat. No. 5,555,672 issued Sep. 17, 1996, describes the previously disclosed in-ground termite detector/server, a number of alternative embodiments that enable it to be used in above-ground applications, and guides for directing termite travel. These guides do not recruit termites to the detector/server, but make it difficult for them to leave once they arrive. A still later patent granted to the same inventors, U.S. Pat. No. 5,573,760 issued Nov. 12, 1996 again describes the originally disclosed in-ground termite detector/server alone.
Although the detector/server combination disclosed in these patents is not known to be marketed at the present time, all of the in-ground termite detector/servers placed on the market in the United States over the past four years share important elements and characteristics with it. For example, all of these detector/servers are, for practical purposes, multifunctional devices.
Factors Affecting Cost
The new approaches to termite control that have followed the ban on cyclodiene termiticides are significantly more costly to the consumer than the pre-1987 approaches they replace. As a result, homeowners find it increasingly difficult to afford many of the newer treatment methods. Many medical institutions, municipalities and public school systems, whose plant maintenance budgets are already stretched thin, find themselves in the same spot.
The sharp increase in cost for the new termite treatment approaches has a number of causes; some unique to the approach involved. But one major cause common to all of them involves labor. Each requires the services of highly skilled and experienced technicians. Each also requires more of the technician""s time than before. This is especially the case for termite detection and baiting methodologies.
Another major cost booster common to all of the termite detection and baiting systems involves the generally cryptic nature of their convertible detector/servers. Of particular interest is the fact that the inspection of these termite detector/servers requires, as a prerequisite, the completion of several non-trivial, time-consuming and physically challenging tasks.
For example, it is necessary to first dig some of these detector/servers out of the ground e.g., U.S. Pat. No. 5,695,776. In other cases a cap must first be removed before extracting an interior bait cartridge e.g., U.S. Pat. No. 5,573,760. In yet another case the interior bait is left undisturbed but a cap must first be removed to expose the interior termite food source e.g., WO9726788A1. All of the caps involved, except that of U.S. Pat. No. 5,573,760, which is not known to be presently on the market, stipulate the use of special keys to prevent unauthorized access to the interior of the detector/server.
Once the interiors of these detector/servers are exposed, the inspector must still visually examine them for evidence of active termites. This process is often complicated by extraneous factors such as the presence of other organisms and debris.
Human Factors
It is generally possible to establish, from an analysis of the various steps involved in a given task, how well the task is likely to be performed once by an average worker. It is more difficult to establish how well such a task is likely to be performed repetitively because, aside from the complexity of the task itself, repetition introduces other variables that must also be accounted for.
It is well known in the field of human factors engineering that the performance of complex, repetitive operations varies based on the nature of their accompanying psychological and physiological rewards and detractors. For example, positive psychological rewards have a motivating influence and consistently lead to improvements in performance. Conversely, negative psychological detractors, or physiological detractors inherent to complex, repetitive task schemata, or those that typically cause the operator to experience pain and discomfort when the operation is performed, have a demotivating influence and consistently lead to performance degradation.
In the case of the inspection of termite detector/servers that are currently on the market, the inspector receives a positive psychological reward when a previously quiescent detector is discovered to contain active termites. The positive reward presumably derives from the fact that the inspection process has successfully revealed important, new information. This reinforces its worth and that of the inspector as well.
On the other hand, inspecting a presently quiescent detector/server that had been quiescent on all previous inspections constitutes an annoying psychological detractor the first time, but develops into an increasingly severe psychological detractor with the number of consecutively quiescent detector/servers inspected. These effects are of little or no consequence for trivial tasks that are performed infrequently, but they increase in significance with the complexity of the task and its frequency of repetition. The inspection of the detector/server may be perceived as a waste of the inspector""s time since it only reinforces negative data. This lowers the worth of the inspection process, and by inference, that of the inspector as well.
Numerous studies have been published describing the results of field trials using one or more of the currently marketed detector/servers. Typically, these papers have shown that, even in areas known to harbor active subterranean termite infestations, it is not unusual for only a small fraction of the deployed detector/servers to become infested with active termites. Obviously, for areas devoid of active termites, where the detector/servers serve as early warning devices, none of the detector/servers will become infested until termite foragers encroach on the area, a process that may not develop for years. Despite this, it is critically important that each detector/server be inspected carefully and completely on the chance that active termites will be found. The risk of performance degradation, under such conditions, is very great.
In addition to the psychological detractors common to the currently marketed termite detector/servers, they are also plagued with a number of physiological detractors. The inspection of each termite detector requires the articulation of all the major joints in the upper and lower extremities as well as flexion of the cervical, thoracic and lumbar spine. These articulations are, for example, a necessary part of wielding a shovel to dig up a detector/server and of bending over or squatting down to pick it up for inspection. For capped detector/servers, the inspector either bends over, squats down or kneels, removes the cap, and either withdraws the contents or crouches closer to the detector/server before conducting a visual examination.
These physically challenging articulations suggest that an individual with a perfectly healthy musculature and spine, and with no diseases of the joints, may naturally experience some degree of pain and discomfort during the inspection of a single detector/server. Individuals with orthopedic dysfunctions will experience even greater degrees of pain and discomfort, depending on the location and severity of their disease. Such persons will have considerable difficulty performing these steps consistently well, if they can perform them at all.
According to the Arthritis Foundation, nearly 1 in 7 Americans is afflicted with arthritis, making this disease one of the most prevalent chronic health problems and the number one cause of limitation in movement in the United States. Furthermore, anyone can get arthritis. It affects people in all age groups. A recent study indicates that the prevalence of arthritis or other rheumatic condition within the United States is expected to climb to 59.4 million, or 18.2% of the population by the year 2020. It should be clear, therefore, that complex tasks, especially those involving repetition, should be designed to minimize the incidence of pain and discomfort for those operators who may be afflicted with arthritis or related disorders.
Mild arthritis will not prevent an inspector from performing infrequent inspections of one or two of any of the detector/servers now on the market. Unfortunately, they are not designed to be inspected infrequently, nor one or two at a time. A successful termite technician can be expected to spend several hours a day inspecting for termite activity at various client locations. Under such conditions, with the orthopedic manipulations required to inspect these devices, even the mildest form of arthritis might become a debilitating handicap within a short period.
These orthopedic manipulations also occur prior to the most critical part of the inspection process, namely the visual examination of the bait material for evidence of active termites. With the detector/servers currently on the market, the inspector is required to assume the role of a skilled field entomologist, marshalling a depth of knowledge, experience and an educated eye to visually scan for evidence of termite activity.
Inspecting the interior of an open, subterranean but non-removable bait station for the presence of termites from a crouching position, as required by one style of detector/server, or a removable detection stake or cartridge from other styles of detector/servers, requires excellent lighting and good visual acuity. If the inspector is visually impaired, or if light conditions are unfavorable, a satisfactory inspection is impossible without supplementary lighting, corrective eyewear and/or the use of magnification aids. During periods of high exterior temperatures and/or humidity, the use of corrective eyewear or magnification aids becomes more problematic, increasing the risk of poor performance on the part of the inspector.
The net of these considerations is that, owing to certain common design features, these termite detector/servers present a number of unacceptable negative physiological detractors that will be felt by all persons. For those with even minor disabilities, i.e., for a sizeable fraction of the available work force, the user-unfriendly character of these devices will likely be so serious that quality of service must be sacrificed at once in order to avoid an unbearable level of discomfort and pain.
As in the case of the psychological detractors previously discussed, these negatives should be expected to result in serious performance degradations. Degradations in performance normally expected from both sets of causes would, for example, include reporting skipped stations as inspected and reporting incomplete inspections as though a thorough inspection had been done.
Strong circumstantial evidence exists that the manufacturers of these devices are aware that inspections of their detector/servers may be prone to performance degradation. This evidence rests chiefly on the steps these manufacturers have been observed to take to limit the difficulties associated with the inspection process and mitigate the risks of skipped or incomplete inspections.
For example, hand-held computers equipped with scanning devices are often promoted as labor saving aids to the manual inspection process. However, in some cases they are actually little more than compliance enforcement tools that effectively prevent the false reporting of skipped stations and their use imposes an additional workload on the inspector, rather than the expected reduction. Ironically, far from mitigating over all risk, reliance on these accessories ignores the issues of task rewards and detractors and increases the labor and tedium of the inspection process. Furthermore, even the most ingenious compliance enforcement programs are subject to manipulation and circumvention in the hands of clever and disenchanted operators. Finally, they fail to guarantee that the inspector will perform the remaining steps of inspection in a competent and thorough fashion.
In another approach taken to limit the difficulties associated with inspecting existing in-ground termite detector/servers, the recommended interval between each termite detection unit is lengthened, so that fewer detector/servers are prescribed for a given site. Applicant""s field testing has consistently shown that the maximum interval between detectors should not exceed 1.5 meters. The termite detector/servers on the market today, however, generally recommend an interval on the order of from 3 to 10 meters.
Although ignoring the difficulties involved in inspecting each detector/server, lengthening the recommended interval between each detector/server does reduce the total of such difficulties that will be encountered at a given site. Unfortunately, the sensitivity of the detector/server installation suffers greatly in the process. It is important to include the perimeters of privacy fences, detached sheds, and such things as woodpiles in the detection zone, since many termite infestations begin at these locations. The emphasis on placing as few detector/servers as possible, however, generally rules these areas out in favor of a zone around the most important structure at the site.
Another approach has been to de-emphasize the use of in-ground detectors in favor of above-ground devices such as that disclosed in U.S. Pat. No. 5,832,658 issued Nov. 10, 1998. Above-ground termite monitors are also discussed in a number of recent scientific studies. However, the use of above-ground termite monitors and bait servers as detectors is of questionable utility, since their success means that termites are already infesting the entity being monitored, and the important early warning potential of an extensive in-ground termite detection system is sacrificed.
U.S. Pat. No. 5,815,090 issued Sep. 29, 1998 proposes yet another approach to resolving the difficulties involved in manually inspecting the currently marketed inground termite detector/servers. The system disclosed in that patent takes the human inspector out of the picture altogether, in favor of a fully computerized termite sensing and reporting system. Computer-inspected termite sensors, comprised of termite edible material and an electrical conductor, are inserted into the soil to form a termite detection zone much the way the manually inspected detector/servers are.
The electrical conductor of the computer-inspected termite sensor is arranged in the form of a bridging circuit that is disrupted when termites feed on it. The sensor is attached to a computer whose software is capable of interpreting the electrical signals from the sensor and registering the presence of termites. Once such a system is installed at a site, its computer could be programmed to automatically dial a remote office to report the presence of termites, including their precise location within the site.
With this system the high costs associated with manual inspections of in-ground detector/servers are exchanged for the high costs of sophisticated computer-inspected termite sensors and their associated electronic accessories. Considering the severity of the difficulties associated with the inspection of the in-ground detector/servers now on the market, and assuming that these difficulties cannot be remedied within the framework of a manual inspection program, this invention would appear to offer a viable and reasonable alternative. At least it addresses the rewards/detractors issue, and conceivably improves the accuracy of the inspection process.
Rather than improving on existing manual inspection approaches, the inventor of U.S. Pat. No. 5,815,090 concluded that a computerized system, without human inspectors, stands a greater chance of success. In the summary provided with that patent the inventor noted that the reduced or eliminated need for manual inspections may allow for more comprehensive monitoring.
In other words, more computer-inspected sensors may be installed at a given site than would be practical for an installation of manually inspected detector/servers. This is a reasonable expectation if manually inspected termite detectors are inherently inefficient and this inefficiency is fundamentally linked to the need for human inspectors. In such a case, the inefficiency of manually inspected termite detector/servers is not susceptible to remediation.
A review of the relevant scientific literature published over the past 20 years has failed to find even one paper that addresses the physiological detractors of the human inspector/termite detector interface. Similarly, none of the termite-related patents issued by the U.S. Patent Office since 1971 appears to make that interface more efficient. Instead, these studies and inventions either ignore the problem, make it worse by adding to the human inspector""s workload, or propose new interfaces that eliminate human inspectors.
It is not obvious that remedial measures to date, capable of eliminating most or all of these physiological detractors, are available. Otherwise, these scientists and inventors would have discovered such measures, reported on them, and exploited their potential.
It is desired to provide an improved termite monitoring and detection apparatus that takes into account physiological detractors, provides an early indication of the presence of termites, and provides an effective suppression of termites.
The present invention achieves technical advantages as an improvement over the prior art in the field of detecting, concentrating, and suppressing subterranean termites. Specifically, the invention takes advantage of certain instinctive behaviors of subterranean termites, and of certain innate visual faculties of human observers directly applicable to the field of termite control. The present invention uses these to make the process of subterranean termite detection easier and more accurate, and to facilitate the concentration of termites, and the delivery of toxicants to them, for the purposes of suppressing the termite colony.
Subterranean termites nest and forage within an extensive, closed, social cuticle. When a given subterranean termite colony locates a fresh source of food it incorporates that source into its social cuticle by extending the latter""s boundaries to include the boundaries of the new source of food. In the process, the termites seal any openings in the food source that would otherwise expose the colony to the threat of predation or dehydration.
The present invention orchestrates the use of three distinct devices to detect, concentrate and treat subterranean termites. Those experienced in the field of social insect behavior will note that the present invention could be applied to other wood destroying insects as well.